The invention is related to a process for the adjustment of a travel sensor for a vacuum brake booster for automotive vehicle brake systems having an anti-locking device. The electrical travel sensor monitors the position of a movable wall which furnishes the boosting power of the vacuum brake power booster. In particular, the invention relates to a process for the adjustment of the desired axial distance between an actuating element of the travel sensor and the movable wall.
It is, for example, known from the German patent application published without examination, No. 3,731,603, corresponding to U.S. Pat. No. 4,826,255, to sense the position of the movable wall in order to safeguard the regular functioning of brake systems with anti-locking device which work as "open" systems. U.S. Pat. No. 5,141,295 filed on Dec. 19, 1989 assigned to the assignee of this application also describes such movable wall sensor for a brake power booster for this purpose.
In these arrangements, a rotary hydraulic pump is provided, which, in one control mode, aspirates hydraulic fluid out of an unpressurized supply tank, and with the wheel valves in the closed condition, delivers the same into the master brake cylinder in order to properly position the brake pedal. For this purpose, a travel sensor, for example, a travel-controlled electric switch, is envisaged which supplies an electrical signal depending on the position of the movable wall to an electronic control system which controls the pumping rate of the pump.
The vacuum brake power booster, in particular its housing, is subject to sizable working tolerances which have a negative effect on the functioning of the travel sensor and, in an extreme case, may even lead to the total failure of the brake system.
It is, therefore, the object of the invention to provide a process for the adjustment of the exact position of the electrical travel sensor in respect of the movable wall of a vacuum brake power booster, which affords a virtual elimination of the influence of its working tolerances on the functioning of the travel sensor.